Research On Polishing Slurry Flow During Ultra-Thin Stainless Steel Substrate Chemical Mechanical Polishing

Ultra-thin stainless steel substrate is the ideal flexible display substrate materials, how to reduce the ultra-thin stainless steel substrate surface roughness is a key problem restricting the development of the flexible display. Chemical Mechanical Polishing (CMP) with its ultra precision machining, no damage surface and a good Polishing effect has been widely used in the surface. Domestic and foreign scholars have done a lot of research on chemical mechanical polishing mechanism, but there is little study about polishing slurry flow field distribution and polishing process parameters’effect on the thickness of slurry film and polishing effects during CMP. the system study of ultra-thin stainless steel substrate chemical mechanical polishing process and polishing liquid flow field distribution has become a very urgent task.Around the theme of polishing liquid flow field distribution, this paper was researched different polishing process parameters effect on the thickness of liquid film and polishing quality. Based on relevant theories such as fluid lubrication, it was established ultra-thin stainless steel substrate CMP polishing fluid hydrodynamic model,using MATLAB software to numerical simulation and obtained different polishing process parameters effect on the thickness of liquid film and liquid film pressure influence.At last, it built a high-speed camera test platform, using visualization research to study polishing fluid flow field and verified this model.The main research and conclusions are as follows:(1) analyzed polishing speed effect on slurry film thickness and polishing quality, the results showed that polishing speed effect on slurry film pressure is minimal, and has a significant effect on the thickness of slurry film; The experimental condition in this paper, when the polishing speed is 60 r/min, the polishing quality is optimum, thickness of slurry film change is minimum and polishing liquid flow field distribution uniformity is good.(2) analyzed polishing load effect on the slurry film thickness and polishing quality, the results showed that polishing load have a significant impact on slurry film pressure, thickness of slurry film and polishing quality; The experimental condition in this paper, when the polishing load is 40 N, slurry film thickness change is small, polishing liquid flow field distribution is uniform and the polishing quality is optimum.(3) Polishing pad groove structure effect on the slurry thickness are analyzed. The results showed that groove structure has a significant impact on the liquid film pressure, thickness of liquid film and polishing quality. When the polishing without groove, he slurry film thickness change is bigger, the polishing liquid flow field distribution uniformity is low and polishing quality is poor. When polishing pad with groove the stability of the polishing process and polishing quality are increasing; at the same time, Different groove structure polishing process flow field distribution uniformity and polishing quality by superior to inferior to:compound type> mesh> concentric circular type> radiation type.(4) The size of polishing abrasive effect on slurry film thickness and polishing quality was analyzed. The results showed that polishing abrasive has a significant effects on slurry film thickness and polishing quality. When polishing slurry without abrasive, the liquid film thickness change is bigger, the polishing liquid flow field distribution uniformity is low and the polishing quality is poorer. When polishing slurry with abrasive, liquid film thickness change smaller, better polishing liquid flow field distribution uniformity, the polishing quality is better. Different size of abrasive on polishing liquid flow field distribution uniformity and polishing quality by superior to inferior to:50 nm>250 nm>without abrasive.